Major back-end changes, with front-end tweaks to keep up. 1) Data frames are now accepted at the back-end for data objects, and handled by omxData objects. 2) FIML Ordinal Objective function is now working. Ugly and slow, but working. Speedups will likely be added in the coming days and weeks. 3) Definition variable handling has been altered to accomodate the new setup. This also fixes a bug in handling out-of-order data columns. 4) Back-end API altered to include data object list in omxState object. 5) Minor front-end changes to accomodate data frames and enforce integer pointers.